pretty much all you need to know is on a few handy sites i use:
http://jp-carparts.com/toyota/carlist.php?maker=toyotahttp://www.toyodiy.com/http://www.japaneseusedcars.com/car_spe ... alogue.htmhave a GOOD look through them and all your questions are answered
the sedan/hardtop thing is markII specific as the markII comes both sedan and hardtop whereas the cresta is just a sedan but its own unique shape, and the chaser is a hardtop, interestingly enough tho the chaser and the markII hardtop share the same body lines so the front ends can be swapped without any modification they just bolt on.
the jzx81 markII gt only came as a hardtop, and had both digi and analogue dash, also the chaser and cresta came out jzx81 gt too i guess thats your sedan right there
i have a jzx81 gt if your interested in more info about them